1. Field of the Invention
This invention pertains to the use of halogenated alkyl phosphoric acid salts as emulsifiers for tris-haloaliphatic phosphates and the use of these emulsified phosphates as durable flame retardant finishes for textile materials.
2. Description of the Prior Art
Recent years have witnessed a great interest in and a growing demand for flame retardant textiles and fabrics. Conventional methods and procedures for imparting flame retardant properties to many normally flammable materials involve impregnating or otherwise treating the particular material with an aqueous solution containing a flame retarding agent to be followed by a drying operation, usually at elevated temperatures. The difficulties encountered heretofore have dealt with the choice of the particular flame retarding agent. The reason for this is that most good flame retardants are not miscible or compatible with water. Many of the well known flame retarding agents are organic compounds containing phosphorus or halogen and often do not lend themselves to form aqueous solutions. But in order to take advantage of the excellent flame retardancy provided by these compounds it was necessary to solubilize them in suitable organic solvents and apply the resulting compositions to the fabric to be treated. Not only has this procedure been expensive, but in many cases, the solvent affected the fabric adversely, especially in the presence of certain dyes or other additives in the fabric. Furthermore, solvent recovery and application with its attendant capital expenditures and the limited number of suitable organic solvents have made non-aqueous systems very undesirable. Conversely, use of aqueous compositions provides fewer and less serious problems from a technological point in addition to economic advantages. In effect, flame retardant aqueous compositions can be applied to the desired fabric by relatively simple operations such as exhaust technique, or pad dry cure and the like.
In U.S. Pat. No. 3,729,434 there is disclosed a method of producing fire retardant emulsions by dissolving a halo alkyl phosphate in a substantially water immiscible organic solvent and an oil soluble, metal sulfonate/polyoxyethylene ether blend. It is said that this system will form a stable aqueous emulsion.
U.S. Pat. No. 3,660,582 discloses the use of mono- and bishaloalkyl esters of phosphoric acid, their water soluble salts and mixtures thereof or an aqueous emulsion of such acids and salts or of the corresponding tris compounds as a topically applied flame retardant for melt spun polyester material.
More recently, there have been developed some flame retardant finishes for textiles which are successful even when applied to various cotton/polyester blends. Again these finishes use brominated flame retardants, the most common of which is tris(2,3-dibromopropyl)phosphate. This material possesses good heat and hydrolytic stability. However, it is highly insoluble in water. Therefore, these finishes as well as other finishes previously proposed in the prior art utilize one or more emulsifiers which are necessary to maintain a workable emulsion that contribute nothing to the primary function of the composition or finish, i.e., flame retardancy.
There has now been discovered an emulsifier for the foregoing successful flame retardant finishes which is non-interfering with and can further contribute to the flame retardant efficacy of the textile finish.